When I started using oil pastels and especially Mungyo Gallery a year ago, I got really curious whether they really are lightfast because this info is not available anywhere.
So December 2018 I started my lightfastness home test - such test was described by Ken Leslie and some of Wetcanvas oil pastelists conducted those tests years ago - for example, this link
proves Pentels are not lightfast (no surprise, but still cool experiment) and this one
shows photos where after a year test Van Gogh OPs proved to have good lightfastness and Cray-Pas Expressionist - decent lightfastness, though not perfect.
By the way, in Ken Leslie's test from his book about Oil Pastels published 30 years ago, only Sennelier demonstrated perfect lightfastness. Some colors even in Holbein and Neopastels fades, but just a few.
Anyway, my test went on from December 16, 2018 to October 31, 2019 and after 10 months most colors of Mungyo Gallery didn't change color. At that moment I only had 48 colors from the main set + extra 4 colors from the full set.
But one color, Light Mauve (#255) turned blue-grey. Also four other colors got a little pale, just a bit. Btw, all the numbers written with a pen vanished completely so I wrote them against the colors that changed:
Also some of the colors turned a little pale as well:
I live in St. Petersburg which cannot boast lots of sunlight, but my windows are facing south so I think this test is pretty reliable.
I would like to do a new home test for checking how Pentel, my other light colors of Mungyo Gallery and Sakura Specialist would fare. I know pinks, violets, orange/beige, some blues are prone to fading, so it will be fun to check it and compare the results.
PS: I've also tested my Holbeins, Neopastels and Sakura Specialist, but as I only had small sets of those, they were all bright colors which are of course not going to fade, with all those official ratings the manufacturers provide. But soon I'll get the full set of Sakura Specialist and will check how light colors with lower LF ratings would perform.
If you want to see my instagram post with different text and photos about this test, it's here